Imaging device and imaging control method capable of preventing camera shake

ABSTRACT

There are provided an imaging device and an imaging control method that can achieve both subject-following performance during a shake-correcting operation and a reduction in the size of a lens. The object is achieved by an imaging device including a shake detection unit that continuously detects a shake, a correction unit that corrects a shake of a subject image by moving an imaging lens and an imaging element relative to each other in a direction orthogonal to a direction of an optical axis of an incidence ray according to the detected shake, and a control unit that limits a movable range of relative movement to the inside of a rectangle included in a circle, which is the maximum movable range, in a case where imaging is performed at a certain frame rate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/JP2017/025844 filed on Jul. 18, 2017, which claims priority under 35U.S.C § 119(a) to Japanese Patent Application No. 2016-179437 filed onSep. 14, 2016. Each of the above application(s) is hereby expresslyincorporated by reference, in its entirety, into the presentapplication.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to an imaging device and an imagingcontrol method, and more particularly, to an imaging device and animaging control method that prevent the shake of a taken image caused bya camera shake.

2. Description of the Related Art

An optical image stabilizer (OIS), which can detect the shake of animaging device, correct an image shake by shifting a correction lensaccording to the detected shake, and obtain a sharp image, is known inregard to an imaging device, such as a digital camera.

JP3162126B discloses a technique that reduces the size of a lens barrelby forming the movable range of a correction optical system in acircular shape or an octagonal shape in a camera using OIS.

SUMMARY OF THE INVENTION

However, in a case where the movable range of a correction lens isformed in a circular shape or an octagonal shape and a panning operationor a tilt operation is performed in a state where the correction lens ispresent at a position displaced from a movement center, a correctablerange in a horizontal direction and a correctable range in a verticaldirection affect each other due to the positions thereof. For thisreason, shake correction suddenly stops. For example, a moving distancein the horizontal direction is reduced at a position displaced in thevertical direction. For this reason, there is a problem that it isdifficult to capture a subject on a finder or a display.

The invention has been made in consideration of the above-mentionedcircumstances, and an object of the invention is to provide an imagingdevice and an imaging control method that can achieve bothsubject-following performance during a shake-correcting operation and areduction in the size of a lens.

In order to achieve the object, an imaging device according to an aspectcomprises: an imaging unit that includes an imaging element converting areceived subject image into an image signal and an imaging lens allowingan incidence ray, which is incident from a subject, to be incident onthe imaging element, at least one of the imaging lens or the imagingelement being movable in a direction orthogonal to a direction of anoptical axis of the incidence ray, and a maximum movable range ofrelative movement of the imaging lens and the imaging element being acircle; a shake detection unit that continuously detects a shake of theimaging unit; a correction unit that corrects a shake of the subjectimage by moving the imaging lens and the imaging element relative toeach other according to the detected shake; and a control unit thatlimits the movable range of the relative movement performed by thecorrection unit to the inside of a rectangle included in the circle in acase where imaging is performed at a certain frame rate by the imagingunit.

According to this aspect, the movable range of the relative movementperformed by the correction unit is limited to the inside of a rectangleincluded in the circle, which is the maximum movable range, in a casewhere imaging is performed at a certain frame rate by the imaging unit.Accordingly, both subject-following performance during ashake-correcting operation and a reduction in the size of the lens canbe achieved.

It is preferable that the control unit sets the movable range of therelative movement to the inside of the circle in a case where a staticimage is to be taken. Accordingly, a shake correction effect can beensured to the maximum extent in a case where a static image is to betaken.

The imaging device preferably further comprises a display unit thatdisplays a live view image allowing a user to check the subject image,and it is preferable that the control unit limits the movable range ofthe relative movement to the inside of the rectangle in a case where thelive view image is to be taken. Accordingly, a live view image of whichframes are connected to each other well can be taken.

It is preferable that the control unit limits the movable range of therelative movement to the inside of the rectangle in a case where a videois to be taken. Accordingly, a video of which frames are connected toeach other well can be taken.

It is preferable that the control unit limits the movable range of therelative movement to the inside of the rectangle in a case wherecontinuous imaging for continuously taking static images is to beperformed. Accordingly, continuous static images of which frames areconnected to each other well can be taken.

It is preferable that the rectangle is inscribed in the circle. Further,it is preferable that the rectangle is a square. Accordingly, themovable range can be made as large as possible.

It is preferable that the rectangle has sides parallel to a horizontaldirection and a vertical direction of an imaging field of view of theimaging unit, respectively. Accordingly, subject-following performancecan be ensured even in a case where a panning operation for shaking theimaging device in the horizontal direction and/or a tilt operation forshaking the imaging device in the vertical direction is performed.

It is preferable that the control unit limits the movable range of therelative movement to the inside of the rectangle after relativepositions of the imaging lens and the imaging element enter therectangle. Accordingly, it is possible to prevent a sense of discomfortin a case where the movable range is to be switched.

It is preferable that the correction unit moves the imaging lens.Further, the correction unit may move the imaging element. This aspectcan be applied to a lens shift type shake correction mechanism and/or asensor shift type shake correction mechanism.

In order to achieve the object, an imaging control method according toanother aspect comprises: an imaging step of imaging a subject by animaging unit that includes an imaging element converting a receivedsubject image into an image signal and an imaging lens allowing anincidence ray, which is incident from the subject, to be incident on theimaging element, at least one of the imaging lens or the imaging elementbeing movable in a direction orthogonal to a direction of an opticalaxis of the incidence ray, and a maximum movable range of relativemovement of the imaging lens and the imaging element being a circle; ashake detection step of continuously detecting a shake of the imagingunit; a correction step of correcting a shake of the subject image bymoving the imaging lens and the imaging element relative to each otheraccording to the detected shake; and a control step of limiting themovable range of the relative movement performed in the correction stepto the inside of a rectangle included in the circle in a case whereimaging is performed at a certain frame rate in the imaging step.

According to this aspect, the movable range of the relative movementperformed by the correction unit is limited to the inside of a rectangleincluded in the circle, which is the maximum movable range, in a casewhere imaging is performed at a certain frame rate by the imaging unit.Accordingly, both subject-following performance during ashake-correcting operation and a reduction in the size of the lens canbe achieved.

Further, a program that allows a computer to perform the above-mentionedimaging control method and a computer-readable non-temporary recordingmedium in which the program is recorded are also included in thisaspect.

According to the invention, it is possible to achieve bothsubject-following performance during a shake-correcting operation and areduction in the size of a lens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view showing the appearance of a digitalcamera 200.

FIG. 2 is a rear perspective view showing the appearance of the digitalcamera 200.

FIG. 3 is a block diagram showing the internal configuration of thedigital camera 200.

FIG. 4 is a schematic diagram showing an imaging unit 10.

FIG. 5 is an exploded perspective view of a camera shake-correctionmechanism 116.

FIG. 6 is a front view of the camera shake-correction mechanism 116 fromwhich a cover is removed.

FIG. 7 is a cross-sectional view of main parts of the camerashake-correction mechanism 116.

FIG. 8 is a block diagram showing an example of the electricconfiguration of a camera shake-correction control unit 117.

FIG. 9 is a diagram illustrating an influence of a correctable range.

FIG. 10 is a diagram showing the movable range of OIS of the digitalcamera 200.

FIG. 11 is a flowchart showing processing of a camera shake-correctionmethod for the digital camera 200.

FIG. 12 is a flowchart showing a method of setting the movable range ofOIS according to a first embodiment.

FIG. 13 is a diagram illustrating a correctable range of a quadrangleSQ.

FIG. 14 is a flowchart showing a method of setting the movable range ofOIS according to a second embodiment.

FIG. 15 is a flowchart showing a method of setting the movable range ofOIS according to a third embodiment.

FIG. 16 is a diagram showing a horizontal direction, a verticaldirection, and a quadrangle SQ of an imaging field of view according tothe first to third embodiments.

FIG. 17 is a diagram showing a horizontal direction, a verticaldirection, and a quadrangle SQ of an imaging field of view according toanother embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will be described in detail belowwith reference to the accompanying drawings.

<Overall Structure of Digital Camera>

FIGS. 1 and 2 are a front perspective view and a rear perspective viewshowing an example of the appearance of a digital camera 200 that is animaging device according to this embodiment, respectively.

The digital camera 200 includes a camera body 202 and an imaging lens204 that is mounted on the front surface of the camera body 202. Theimaging lens 204 may be adapted to be attachable and detachable by alens-side mount and a camera-side mount.

A shutter button 208 is provided on the upper surface of the camera body202.

The shutter button 208 is formed of a two-stage button including aswitch S1 that is turned on in a case where the shutter button 208 ishalf pressed and a switch S2 that is turned on in a case where theshutter button 208 is fully pressed. The digital camera 200 performs anautomatic exposure (AE) operation and an auto focus (AF) operation in acase where the shutter button 208 is half pressed, and performs mainimaging in a case where the shutter button 208 is fully pressed.

Further, an LCD monitor 210 and operation button 212 are provided on therear surface of the camera body 202.

The LCD monitor 210 is a display unit that displays live view images,taken images, imaging conditions of the digital camera 200, or the like.The horizontal direction and the vertical direction of a live view imageand a taken image to be displayed on the LCD monitor 210 are parallel tothe horizontal direction (X direction) and the vertical direction (Ydirection) of the imaging field of view of an imaging unit 10 (the rangeof a taken image), respectively.

The operation button 212 is an operation unit that includes a powerswitch, an imaging mode dial, a camera shake-correction switch, and thelike.

The digital camera 200 has a static image mode, a continuous imagingmode, and a video mode as imaging modes. In the static image mode, onestatic image is taken according to an instruction of the main imaging.In the continuous imaging mode, a plurality of static images are takenat a constant time interval according to an instruction of the mainimaging. Further, in the video mode, a video is taken according to aninstruction of the main imaging.

In the main imaging, an image obtained from imaging (main taken image)is recorded on a recording medium 131 (see FIG. 3). Further, the imagerecorded on the recording medium 131 is played back and displayed on theLCD monitor 210 in a case where the digital camera 200 is set to aplayback mode by the operation of the operation button 212.

<Internal Configuration of Digital Camera>

FIG. 3 is a block diagram showing an example of the internalconfiguration of the digital camera 200. As shown in FIG. 3, the digitalcamera 200 comprises a charge coupled device (CCD) 13, a camerashake-correction device 100, a central processing unit (CPU) 111, amotor driver 115 for focusing, a timing generator 119, a CCD driver 120,an analog signal processing unit 122, an analog/digital (A/D) converter123, an image input controller 124, an image signal processing circuit125, a compression processing circuit 126, a video encoder 127, a bus129, a medium controller 130, a recording medium 131, a memory 132, anAF detection circuit 133, an AE detection circuit 134, and the like, inaddition to the imaging lens 204, the shutter button 208, the LCDmonitor 210, and the operation button 212 having been described above.

The shutter button 208 and the operation button 212 output signals,which correspond to operations, to the CPU 111. The respectivecomponents are operated under the control of the CPU 111, and the CPU111 controls the respective components of the digital camera 200 byexecuting predetermined control programs on the basis of inputs from theshutter button 208 and the operation button 212.

A program read only memory (ROM) is built in the CPU 111, and variousdata and the like required for control are recorded in the program ROMin addition to control programs that are executed by the CPU 111. TheCPU 111 controls the respective components of the digital camera 200 byreading the control programs, which are recorded in the program ROM,into the memory 132 and sequentially executing the control programs.

The memory 132 is used as a temporary storage area for image data andthe like and various work area in addition to an area where a program isexecuted.

The imaging lens 204 is driven by the motor driver 115 for focusing andis moved forward and backward on the optical axis of the imaging lens204. The CPU 111 controls the movement of the imaging lens 204 throughthe motor driver 115 for focusing to perform focusing.

The camera shake-correction device 100 includes a camerashake-correction mechanism 116 (see FIG. 5) that includes avibration-proof lens 12 and a camera shake-correction control unit 117that controls the camera shake-correction mechanism 116. The camerashake-correction device 100 corrects the shake of a subject image of theCCD 13 that is caused by the shake of the digital camera 200. Thedetails of the camera shake-correction mechanism 116 and the camerashake-correction control unit 117 will be described later.

The imaging lens 204 and the vibration-proof lens 12 (an example of animaging lens) allow subject light (an example of an incidence ray),which is incident from a subject, to be incident on the CCD 13 (anexample of an imaging element). The subject light, which is incident onthe CCD 13, forms an image on the light-receiving surface of the CCD 13.The CCD 13 includes the light-receiving surface on which a plurality oflight-receiving elements are arranged in the form of a matrix in the Xdirection and the Y direction forming the imaging field of view, andconverts a subject image, which is formed on the light-receivingsurface, into electrical signals by each of the light-receivingelements.

The CCD 13 outputs electric charges, which are accumulated in eachpixel, line by line as serial image signals in synchronization with avertical transfer clock and a horizontal transfer clock that aresupplied from the timing generator 119 through the CCD driver 120. TheCPU 111 controls the drive of the CCD 13 by controlling the timinggenerator 119.

The electric charge accumulation time (exposure time) of each pixel isdetermined depending on an electronic shutter-driving signal that isapplied from the timing generator 119. The CPU 111 gives an instructionof electric charge accumulation time to the timing generator 119.

Further, the output of an image signal is started in a case where thedigital camera 200 is set to an imaging mode. That is, in a case wherethe digital camera 200 is set to the imaging mode, the output of animage signal is started to display a live view image on the LCD monitor210. The live view image is taken at a frame rate of, for example, 30frames per second. In a case where the main imaging is instructed, theoutput of an image signal for the live view image is temporarilystopped. In a case where the main imaging is ended, the output of animage signal for the live view image is started again. Due to this liveview image, a user can check a subject image and set the composition ofthe main imaging. An electronic finder may be provided on the rearsurface of the digital camera 200, and the live view image may bedisplayed on the electronic finder.

An image signal, which is output from the CCD 13, is an analog signal,and this analog image signal is received in the analog signal processingunit 122.

The analog signal processing unit 122 includes a correlated doublesampling circuit and an automatic gain control circuit. The correlateddouble sampling circuit removes noise included in the image signal, andthe automatic gain control circuit amplifies the image signal, fromwhich noise is removed, with a predetermined gain. The analog imagesignal, which is subjected to required signal processing by the analogsignal processing unit 122, is received in the A/D converter 123.

The A/D converter 123 converts the received analog image signal into adigital image signal that has a gradation width corresponding to apredetermined bit. This image signal is so-called RAW data, and has agradation value that represents the density of R (Red), G (Green), and B(Blue) for each pixel.

Since a line buffer having a predetermined capacity is built in theimage input controller 124, the image input controller 124 accumulatesimage signals corresponding to one frame that are output from the A/Dconverter 123. The image signals corresponding to one frame, which areaccumulated in the image input controller 124, are stored in the memory132 through the bus 129.

The image signal processing circuit 125, the compression processingcircuit 126, the video encoder 127, the medium controller 130, the AFdetection circuit 133, the AE detection circuit 134, and the like areconnected to the bus 129 in addition to the CPU 111, the memory 132, andthe image input controller 124; and these can send and receiveinformation to and from each other through the bus 129.

The image signals corresponding to one frame, which are stored in thememory 132, are received in the image signal processing circuit 125 inorder of points (in order of pixels).

The image signal processing circuit 125 performs predetermined signalprocessing on the image signals that are received in order of points andcorrespond to the respective colors of R, G, and B, and generate imagesignals (Y/C signals) that include brightness signals Y and colordifference signals Cr and Cb.

The AF detection circuit 133 receives the image signals, which arestored in the memory 132 through the image input controller 124 andcorrespond to R, G, and B, according to a command of the CPU 111 andcalculates a focus evaluation value required for AF control. The AFdetection circuit 133 includes a high-pass filter that allows only ahigh-frequency component of a G signal to pass, an absolute valueprocessing unit, a focus area extraction unit that extracts signals of apredetermined focus area set on a screen, and an integration unit thatintegrates absolute value data of the focus area; and outputs theabsolute value data of the focus area, which is integrated by theintegration unit, to the CPU 111 as the focus evaluation value. The CPU111 searches for a position where the focus evaluation value output fromthe AF detection circuit 133 becomes maximum, and focuses on a mainsubject by moving the imaging lens 204 to the position.

The AE detection circuit 134 receives the image signals, which arestored in the memory 132 through the image input controller 124 andcorrespond to R, G, and B, according to a command of the CPU 111 andcalculates an integrated value required for AE control. The CPU 111calculates a brightness value from the integrated value, and obtains anexposure value from the brightness value. Further, the CPU 111determines an F number and a shutter speed from the exposure valueaccording to a predetermined program diagram.

The compression processing circuit 126 performs compression processing,such as JPEG (Joint Photographic coding Experts Group), on an input Y/Csignal according to a compression command output from the CPU 111, andgenerates compressed image data. Further, the compression processingcircuit 126 performs decompression processing having a predeterminedformat on input compressed image data according to a decompressioncommand output from the CPU 111, and generates uncompressed image data.

The video encoder 127 controls a display on the LCD monitor 210according to a command output from the CPU 111.

The medium controller 130 controls the reading/writing of data from/on arecording medium 131 according to a command output from the CPU 111. Therecording medium 131 may be attachably and detachably mounted on thecamera body, or may be built in the camera body. In a case where therecording medium 131 is to be attachably and detachably mounted on thecamera body, a card slot is provided in the camera body and therecording medium 131 is used while being loaded in the card slot.

<Structure of Camera Shake-Correction Mechanism>

FIG. 4 is a schematic diagram showing an imaging unit 10. As shown inFIG. 4, the imaging unit 10 includes the imaging lens 204, thevibration-proof lens 12, and the CCD 13. An optical system of thedigital camera 200 includes the imaging lens 204 and the vibration-prooflens 12. The imaging lens 204 is composed of two lenses 204A and 204B.

The CCD 13 is disposed on an optical axis 14 of the optical system, andconverts a subject image into electrical signals as described above.Since a subject image is moved on the CCD 13 during exposure in a casewhere a camera shake occurs on the imaging unit 10, electrical signalsof a blurred image are generated from the CCD 13. A camera shake isvibration that is generated on the digital camera 200 (imaging unit 10)in a case where a user takes an image by the digital camera 200.

The digital camera 200 is adapted to be switched to a camerashake-correction mode and a camera shake-correction-unavailable mode bythe operation button 212, separately from the setting of the imagingmode. In the camera shake-correction mode, the movement of thevibration-proof lens 12 is controlled so the shake of the subject imageis canceled. In the camera shake-correction-unavailable mode, thevibration-proof lens 12 is controlled so as to stop.

The digital camera 200 comprises an angular velocity sensor 50 (see FIG.8, an example of a shake detection unit) that is provided in the camerabody or a lens assembly and continuously detects the shake of theimaging unit 10. The angular velocity sensor 50 detects a shake in the Xdirection and the Y direction, and outputs a signal that represents theangular velocity of the shake. An angular acceleration sensor, whichoutputs a signal representing an angular acceleration, may be usedinstead of the angular velocity sensor 50.

In a case where a camera shake does not occur on the imaging unit 10,the optical axis of the vibration-proof lens 12 coincides with theoptical axis 14 of the optical system. In a case where the camera shakeof the imaging unit 10 in the X direction and/or the Y direction isdetected by the angular velocity sensor 50, the vibration-proof lens 12is moved in the X direction and/or the Y direction orthogonal to theoptical axis 14 (the direction of the optical axis) according to thedegree and direction of the camera shake. An arrow shown in FIG. 4indicates movement in +X direction and −X direction. Accordingly, sincea subject image to be formed on the CCD 13 is substantially in a stopstate, signals representing a sharp image are output from the CCD 13.

FIG. 5 is an exploded perspective view of the camera shake-correctionmechanism 116 (an example of a correction unit) for moving thevibration-proof lens 12, and FIG. 6 is a front view of the camerashake-correction mechanism 116 from which a cover is removed. Further,FIG. 7 is a cross-sectional view of main parts of the camerashake-correction mechanism 116.

The imaging lens 204 is mounted on the lens barrel 15. The lens barrel15 is fixed to the lens assembly. Further, the lens barrel 15 isprovided with a main guide shaft 16 that extends in the X direction, amain guide shaft 17 that extends in the Y direction, an X slider 18 thatis slidable in the X direction, and a Y slider 19 that is slidable inthe Y direction. The X slider 18 and the Y slider 19 have asubstantially L shape in a plan view.

A pair of shaft holes 18 a is formed in the X slider 18, and these shaftholes 18 a are slidably fitted to the main guide shaft 16. Likewise, apair of shaft holes 19 a of the Y slider 19 is slidably fitted to themain guide shaft 17.

Further, a pair of shaft holes 18 b is formed in the X slider 18. Theshaft holes 18 b are slidably fitted to a sub-guide shaft 20 extendingin the Y direction. A pair of shaft holes 19 b of the Y slider 19 isslidably fitted to a sub-guide shaft 21 extending in the X direction.

A flat ring-shaped coil 22 is mounted on the X slider 18. Likewise, acoil 23 is also mounted on the Y slider 19. A yoke 25 in which apermanent magnet 26 is mounted is mounted on the lens barrel 15 togenerate an electromagnetic force acting in the X direction betweenitself and the coil 22. A yoke and a permanent magnet, which generate anelectromagnetic force acting in the Y direction between the coil 23 andthem, are not shown.

A lens holder 30 holds the vibration-proof lens 12. A pair of holes 30 ais formed in the lens holder 30, and both ends of the sub-guide shaft 21extending in the X direction are fitted to these holes 30 a and arefixed by an adhesive or the like so that the sub-guide shaft 21 is notmoved. Likewise, the sub-guide shaft 20 is firmly held by a pair ofholes 30 b.

A cover 32 is disposed on the lens holder 30 so as to hide the X slider18 and the Y slider 19. The cover 32 is placed on a step 15 a of thelens barrel 15. Two permanent magnets 33 and 34 are mounted on the innersurface of the cover 32. The permanent magnet 33 faces the yoke 25, andthe permanent magnet 34 faces another yoke (not shown).

As shown in FIG. 7, the permanent magnets 26 and 33 are positioned onboth sides of the coil 22 and a bent piece 25 a of the yoke 25 isinserted into the coil 22. In a case where current flows in the coil 22,an electromagnetic force is generated from a magnetic field generatedaround the coil 22 and the magnetic fields of the permanent magnets 26and 33. This electromagnetic force acts in +X direction or −X directionaccording to the direction of the current of the coil 22 and moves the Xslider 18 in +X direction or −X direction. Likewise, in a case wherecurrent flows in the coil 23, the Y slider 19 is moved in +Y directionor −Y direction by an electromagnetic force that is generated from amagnetic field generated around the coil 23 and the magnetic fields ofthe permanent magnet (not shown) and the permanent magnet 34.

Further, an X Hall element 40 and a Y Hall element 41 are received inholes 15 b and 15 c of the lens barrel 15, respectively. The X Hallelement 40 generates a voltage in response to the magnetic field of asmall magnet 42 embedded on the lower surface of the X slider 18. Thisvoltage corresponds to the position of the X slider 18 in the Xdirection. Furthermore, the Y Hall element 41 also generates a voltagein response to the magnetic field of a small magnet 43 embedded on thelower surface of the Y slider 19, and this voltage corresponds to theposition of the Y slider 19 in the Y direction.

The X Hall element 40 and the Y Hall element 41 generate signals in thevoltage range of, for example, 0 to 5 V according to the position of thevibration-proof lens 12. In a state where the X slider 18 is positionedat an X reference position and the Y slider 19 is positioned at a Yreference position, the optical axis of the vibration-proof lens 12coincides with the optical axis 14 of the optical system and both theoutput signals of the X Hall element 40 and the Y Hall element 41 are2.5 V (reference voltage) that are a reference voltage.

<Action of Camera Shake-Correction Control Unit>

In a case where the power source of the digital camera 200 is turned on,the camera shake-correction control unit 117 (see FIG. 2) sets a controltarget value signal to a reference voltage (2.5 V). Then, the camerashake-correction control unit 117 performs the feedback control of thedirection and magnitude of current to be supplied to the coils 22 and 23so that the output signals of the X Hall element 40 and the Y Hallelement 41 reach the reference voltage set as the control target valuesignal. Due to this feedback control, the X slider 18 is moved towardthe X reference position and the Y slider 19 is moved toward the Yreference position. In a case where the X slider 18 and the Y slider 19are set to the reference positions, the optical axis of thevibration-proof lens 12 coincides with the optical axis 14 of theoptical system.

In the camera shake-correction-unavailable mode, the control targetvalue signal is maintained at the reference voltage even though a camerashake occurs. Accordingly, the vibration-proof lens 12 is being stoppedeven though a camera shake occurs.

On the other hand, in the camera shake-correction mode, thevibration-proof lens 12 is moved together with the lens holder 30according to a camera shake. In a case where a camera shake occurs, theangular velocity sensor 50 generates angular velocity signals in the Xdirection and the Y direction. The angular velocity signals in the Xdirection and the Y direction are individually integrated, and areconverted into angle signals in the X direction and the Y direction,respectively. The angle signal is converted into a lens displacementsignal corresponding to the linear movement of the vibration-proof lens12 that is required to correct an image shake corresponding to thisangle (shake angle). The obtained lens displacement signal is added tothe reference voltage (2.5 V), and becomes a control target valuesignal.

Here, since the lens displacement signal has a plus sign or a minus signaccording to the direction of a camera shake, the control target valuesignal fluctuates from the reference voltage (2.5 V) as the middle.

For example, in a case where a camera shake occurs in +X direction, alens displacement signal required to correct the camera shake is addedto the reference voltage and a control target value signal iscalculated. Then, the direction and magnitude of the current of the coil22 are determined so that the output signal of the X Hall element 40becomes the control target value signal. An electromagnetic force in −Xdirection acts on the coil 22 due to a magnetic field, which isgenerated in a case where current flows in the coil 22, and the magneticfields of the permanent magnets 26 and 33. The X slider 18 is movedalong the main guide shaft 16 in −X direction by this electromagneticforce. Further, since the X slider 18 is connected to the lens holder 30through the sub-guide shaft 20, the X slider 18 pushes the lens holder30 in −X direction.

Here, the sub-guide shaft 21 fixed to the lens holder 30 is guided bythe shaft holes 19 b of the Y slider 19. Accordingly, the X slider 18and the lens holder 30 are moved together while being guided by the mainguide shaft 16 and the pair of shaft holes 19 a of the Y slider 19.

In a case where the X slider 18 is moved to a lens positioncorresponding to the control target value signal, the output signal ofthe X Hall element 40 corresponds to the control target value signal.Accordingly, a subject image formed on the CCD 13 is not moved much.Therefore, electrical signals of a clear image are generated from theCCD 13.

In a case where a camera shake is stopped, centering control isperformed so that the lens displacement signal gradually returns to 0.As a result, the control target value signal becomes the referencevoltage (2.5 V), and the direction and magnitude of the current of thecoil 22 are determined so that the output signal of the X Hall element40 returns to the reference voltage. Accordingly, the X slider 18 isgradually moved toward the X reference position. After the X slider 18returns to the X reference position, the direction and magnitude of thecurrent of the coil 22 are controlled so that the X slider 18 ismaintained at the X reference position. Since the lens holder 30 ismoved together with the X slider 18, the lens holder 30 is in a statewhere the optical axis of the vibration-proof lens 12 coincides with theoptical axis 14 of the optical system.

Further, in a case where a camera shake in −X direction occurs, apositive lens displacement signal having a value corresponding to thedegree of a camera shake is added to the reference voltage and a controltarget value signal is calculated. The direction and magnitude of thecurrent of the coil 22 are determined so that the output signal of the XHall element 40 becomes the control target value signal. In a case wherecurrent flows in the coil 22, the X slider 18 is moved along the mainguide shaft 16 in +X direction. In a case where the camera shake in −Xdirection is removed, the X slider 18 gradually returns to the Xreference position and is maintained at the X reference position. In acase where the X slider is positioned at the X reference position, theoptical axis of the vibration-proof lens 12 coincides with the opticalaxis 14 of the optical system.

The same applies to a camera shake in the Y direction. In regard to thecamera shake in the Y direction, the Y slider 19 is moved in the Ydirection by the coil 23. In this case, the lens holder 30 is pushed inthe Y direction through the sub-guide shaft 21. The Y slider 19 isguided by the main guide shaft 17, and the sub-guide shaft 20 of thelens holder 30 is guided by the shaft holes 18 b of the X slider 18.Since the movement of an image caused by a camera shake in the Ydirection is prevented in a case where the lens holder 30 is moved inthe Y direction together with the Y slider 19, a subject image to beformed on the CCD 13 is substantially stopped. In a case where thecamera shake in the Y direction is removed, the Y slider 19 graduallyreturns to the Y reference position by centering control.

Since an actual camera shake occurs in both the X direction and the Ydirection, the lens holder 30 is simultaneously moved in both the Xdirection and the Y direction.

<Electric Configuration of Camera Shake-Correction Control Unit>

FIG. 8 is a block diagram showing an example of the electricconfiguration of the camera shake-correction control unit 117. Thecamera shake-correction control unit 117 includes two systems, that is,a camera shake-correction control unit corresponding to the X directionand a camera shake-correction control unit corresponding to the Ydirection, but both the systems have the same configuration.Accordingly, only the camera shake-correction control unit correspondingto the X direction will be representatively described here.

As shown in FIG. 8, the camera shake-correction control unit 117comprises the angular velocity sensor 50, a high-pass filter (HPF) 152,an analog amplifier 154, an A/D converter 156, an HPF 158, anintegration circuit 160, an integral limiter 162, a phase compensationcircuit 164, a control target value-arithmetic circuit 166, a controltarget value limiter 168, a subtractor 170, an analog amplifier 172, anA/D converter 174, a phase compensation circuit 176, a motor driver 178,a voice coil motor (VCM) 180, a controller 182 (an example of a controlunit), and an operating range-setting unit 184, in addition to theabove-mentioned X Hall element 40. The controller 182 is realized by theoperation of one or a plurality of processors (not shown).

The angular velocity sensor 50 detects the angular velocity of theimaging unit 10 (see FIG. 4) in the X direction and the Y direction.Here, the angular velocity sensor 50 outputs an angular velocity signal(voltage signal), which corresponds to the angular velocity in the Xdirection, to the analog HPF 152. The HPF 152 removes a DC component ofthe input angular velocity signal. The output signal of the HPF 152 isinput to the A/D converter 156 through the analog amplifier 154.

The A/D converter 156 converts the input analog angular velocity signalinto a digital angular velocity signal, and inputs the digital angularvelocity signal to the digital HPF 158. The HPF 158 includes a low-passfilter (LPF) 158A, which detects the reference value of DC, and asubtractor 158B, and the subtractor 158B subtracts the reference value,which is detected by the LPF 158A, from the angular velocity signal.Accordingly, an angular velocity signal having a low frequency, whichcannot be regarded as a camera shake, is removed.

The angular velocity signal, which is output from the digital HPF 158,is integrated by the integration circuit 160 and is converted into anangle (shake angle) signal. That is, the integration circuit 160integrates an input angular velocity signal A1 to converts the inputangular velocity signal A1 into an angle signal A_(n+1). The followingequation is used for this integration.A _(n+1) =α×A1+A _(n)  (Equation 1)

Here, α is a coefficient, and A_(n) is a previous integrated value thatis read from a register.

The tilt angle of the optical system, which is caused by a camera shake,is calculated by this integration. An obtained angle signal A_(n+1) issent to the integral limiter 162. In a case where the tilt angle exceedsa limit angle, the integral limiter 162 cuts a portion of the tilt angleexceeding the limit angle. Accordingly, the maximum value of the anglesignal A_(n+1) becomes the limit angle. This limit angle (the limitvalue of each of the upper limit and the lower limit of a shake angle)is given from the controller 182.

An angle signal, which is output from the integral limiter 162, is inputto the phase compensation circuit 164. The phase compensation circuit164 compensates the delay of an angle signal that is delayed from anactual angle by the arithmetic operation or the like.

The angle signal of which the phase is compensated by the phasecompensation circuit 164 is input to the control target value-arithmeticcircuit 166, and is converted into a control target value thatrepresents a lens position in the X direction to which thevibration-proof lens 12 is to be moved to correct the shake of thesubject image of the CCD 13.

The control target value, which is subjected to an arithmetic operationby the control target value-arithmetic circuit 166, is input to thecontrol target value limiter 168. Since the movable range of thevibration-proof lens 12 is set in the control target value limiter 168by the controller 182, the control target value limiter 168 limits theinput control target value so that a control target value to be outputdoes not exceed the preset movable range.

A control target value, which is output from the control target valuelimiter 168, is input to the positive input of the subtractor 170.

On the other hand, a lens position signal, which represents the currentposition of the vibration-proof lens 12, is input to the negative inputof the subtractor 170. The current position of the vibration-proof lens12 is detected by the X Hall element 40. That is, the X Hall element 40outputs a detection signal (voltage signal) that corresponds to the lensposition of the vibration-proof lens 12. This detection signal is inputto the A/D converter 174 through the analog amplifier 172. The A/Dconverter 174 converts an analog detection signal into a digital signal,and outputs the converted signal to the negative input of the subtractor170 as a lens position signal that represents the current position ofthe vibration-proof lens 12.

The subtractor 170 obtains a difference between the control target valueand the lens position signal (current position), and outputs thisdifference as an operation amount of the vibration-proof lens 12.

The operation amount, which is output from the subtractor 170, issubjected to the phase compensation by the phase compensation circuit176, and is then applied to the motor driver 178. The motor driver 178generates a driving signal, which is subjected to pulse width modulationaccording to the input operation amount, and outputs this driving signalto the VCM 180 that includes the coil 22 shown in FIG. 5.

Accordingly, the vibration-proof lens 12 is driven in the X direction bya moving distance corresponding to the operation amount, and iscontrolled so that the shake of the subject image caused by the camerashake of the digital camera 200 in the X direction does not occur. Acamera shake in the Y direction is also corrected in the same manner asthe camera shake in the X direction.

The controller 182 controls the integration circuit 160, the integrallimiter 162, and the control target value limiter 168. The controller182 acquires an integration result (angle signal) from the integrationcircuit 160, acquires the lens position signal of the vibration-prooflens 12 from the A/D converter 174, acquires a signal, which representsthe movable range, from the operating range-setting unit 184, andacquires signals, which are related to the operation and state of thedigital camera 200, from the CPU 111 (see FIG. 3).

The movable range of the vibration-proof lens 12 is set in the operatingrange-setting unit 184. The controller 182 acquires the movable range,which is set in the operating range-setting unit 184, and sets themovable range in the control target value limiter 168.

Further, in a case where the controller 182 acquires a signalrepresenting the camera shake-correction-unavailable mode from the CPU111, the controller 182 resets the integrated value (angle) of theintegration circuit 160 to 0 and stops the integral operation of theintegration circuit 160 or allows the integration circuit 160 tointegrate 0. Accordingly, since the control target value is 0 in a casewhere the middle position of the operating range of the vibration-prooflens 12 is set as 0, the vibration-proof lens 12 is in a state where thevibration-proof lens 12 is stopped at the middle position of theoperating range.

On the other hand, in a case where the controller 182 acquires a signalrepresenting the camera shake-correction mode from the CPU 111, thecontroller 182 enables the integral operation of the integration circuit160. Further, the CPU 111 outputs the signal of the switch S1, which isturned on in a case where the shutter button 208 is half pressed, andthe signal of the switch S2, which is turned on in a case where theshutter button 208 is fully pressed, to the controller 182.

The controller 182 enables the integral operation of the integrationcircuit 160 in the camera shake-correction mode, but corrects a camerashake to a value that allows the integration result (angle) to beslightly reduced and performs centering control for gradually returningthe vibration-proof lens 12 to an optical center in a period other thana period where the switch S1 or the switch S2 is turned on. Accordingly,vibration-proof accuracy deteriorates but it is possible to avoid a casewhere a vibration-proof operation cannot be performed. On the otherhand, the controller 182 does not perform processing for correcting theintegration result (angle) in a period where the switch S1 or the switchS2 is turned on, and increases vibration-proof accuracy in this period.

<Problems of Camera Shake Correction>

In a case where the maximum movable range of the vibration-proof lens 12has a rectangular shape, the size of an image circle needs to beincreased by an increase in the size of any lens other than thevibration-proof lens 12 to ensure the peripheral illumination viewedfrom an image plane. On the other hand, in a case where the maximummovable range of the vibration-proof lens 12 has a circular shape, animage circle viewed from an image plane is 0.707 times a rectangle.Accordingly, since the size of any lens other than the vibration-prooflens 12 can be made small, an image circle can be minimized.

In this embodiment, the maximum movable range of the vibration-prooflens 12 is a range that is positioned inward from the mechanical limitvalues (mechanical limits) of the movement of the X slider 18 and the Yslider 19 by a predetermined distance, and is a circular range thatcorresponds to the shape of the image circle of the entire lensincluding the imaging lens 204. In a case where the movable range has acircular shape, the effective diameter of the entire lens can beminimized.

However, in a case where a panning operation for shaking the digitalcamera 200 in a horizontal direction and/or a tilt operation for shakingthe digital camera 200 in a vertical direction is performed in a statewhere the optical axis of the vibration-proof lens 12 is present at aposition displaced from the center of the movable range, the correctablerange in the horizontal direction and the correctable range in thevertical direction affect each other due to the positions thereof. Forthis reason, there is a case where camera shake correction suddenlystops. In such a case, it is difficult to capture a subject by the LCDmonitor 210 or the electronic finder (not shown).

FIG. 9 is a diagram illustrating an influence of the correctable range.As shown in FIG. 9, the movable range of the optical axis of thevibration-proof lens 12 is within a circle CR having a radius r. In acase where the optical axis of the vibration-proof lens 12 is present atthe reference position (Y=0) in the Y direction, the optical axis of thevibration-proof lens 12 can be moved to −r from +r in the X direction.

However, in a case where the coordinate of the optical axis of thevibration-proof lens 12 in the Y direction is y1, the movement of theoptical axis of the vibration-proof lens 12 in the X direction islimited between −x1 and +x1. Here, “|r|>|x1|” is satisfied.

On the other hand, these limitations are not applied in a case where themovable range has a rectangular shape. However, in a case where thelimit value of the operating range of the vibration-proof lens 12 isdesigned in regard to a rectangular range, the large image circle of theentire lens should be ensured as described above. For this reason, thediameter of the lens needs to be large. Further, since a large spaceneeds to be ensured around a correction optical system, there is aproblem that the lens barrel is increased in size.

<Camera Shake-Correction Method>

A camera shake-correction method (an example of an imaging controlmethod) in a case where the digital camera 200 is set to the camerashake-correction mode will be described. The movable range of theoptical axis of the vibration-proof lens 12 of the imaging unit 10 willbe written as “the movable range of OIS” below. FIG. 10 is a diagramshowing the movable range of OIS of the digital camera 200. In FIG. 10,an X axis is an axis parallel to the horizontal direction of the imagingfield of view of the imaging unit 10 and a Y axis is an axis parallel tothe vertical direction of the imaging field of view of the imaging unit10.

The maximum movable range of OIS is a range that is present in a perfectcircle CR having a center at the X reference position that is thereference position of the X slider 18 and the Y reference position thatis the reference position of the Y slider 19. In the circle CR, themaximum movable range in the X direction is a range ofX_(GYRO_INTE_GMIN) to X_(GYRO_INTEG_MAX) and the maximum movable rangein the Y direction is a range of Y_(GYRO_INTEG_MIN) toY_(GYRO_INTEG_MAX).

Further, the digital camera 200 has a limited movable range of OIS thatis narrower than the maximum movable range of OIS. The limited movablerange of OIS of this embodiment is a range that has sides parallel tothe horizontal direction and the vertical direction of the imaging fieldof view of the imaging unit 10, respectively, and is present in aquadrangle SQ, that is, a square (an example of a rectangle) inscribedin the circle CR. In the quadrangle SQ, the movable range in the Xdirection is a range of X_(GYRO_INTEG_RECT_MIN) toX_(GYRO_INTEG_RECT_MAX) and the movable range of the movable range inthe Y direction is a range of Y_(GYRO_INTEG_RECT_MIN) toY_(GYRO_INTEG_RECT_MAX).

FIG. 11 is a flowchart showing processing of the camera shake-correctionmethod for the digital camera 200.

First, any one of the circle CR of the maximum movable range or thequadrangle SQ of the limited movable range is determined as the movablerange of OIS by the operating range-setting unit 184 (Step S101). Detailwill be described later, but, basically, as the movable range of OIS,the circle CR is selected at the time of exposure in a case where onlyone static image is to be taken according to the operation of theshutter button 208, and the quadrangle SQ is selected in a case whereimaging is performed at a certain frame rate, such as a case where alive view image is to be taken, a case where a video is to be taken, anda case where continuous imaging for continuously taking static images isto be performed.

After that, imaging to be performed by the imaging unit 10 is started(Step S102, an example of an imaging step). As described above, a liveview image starts to be taken in a case where the digital camera 200 isset to an imaging mode. Further, main imaging is started according to aninstruction of the imaging to be performed by the shutter button 208.

In the main imaging, only one static image is taken in a case where thedigital camera 200 is set to a static image mode. In a case where thedigital camera 200 is set to the continuous imaging mode, a plurality ofstatic images are taken at a constant time interval. In the continuousimaging, for example, six static images are taken per second. Further, avideo is taken in a case where the digital camera 200 is set to a videomode. A video is taken at a frame rate of, for example, 60 frames persecond.

During imaging, the detection of a camera shake to be performed by theangular velocity sensor 50 is performed (Step S103, an example of ashake detection step) and shake correction according to the detectedcamera shake is performed (Step S104, an example of a correction step)in the movable range of OIS (an example of a control step). Afterimaging ends (Step S105), the processing of this flowchart ends.

<Method of Setting Movable Range of OIS>

Next, the detail of a method of setting the movable range of OIS will bedescribed.

First Embodiment

FIG. 12 is a flowchart showing a method of setting the movable range ofOIS according to a first embodiment. Here, it is assumed that thedigital camera 200 is set to the static image mode.

First, it is determined whether or not the movable range of OIS is setto only a circular area limit (Step S11). The digital camera 200 can setthe movable range of OIS to only the inside of the circle CR accordingto the operation of the operation button 212. If the movable range ofOIS is set to only the inside of the circle CR, the operatingrange-setting unit 184 fixes the movable range of OIS to the circle CR(Step S12) and ends the processing of this flowchart.

If the movable range of OIS is not set to only the circular area limit,it is determined whether or not the movable range of OIS is set to onlya quadrangular area limit (Step S13). The digital camera 200 can alsoset the movable range of OIS to only the inside of the quadrangle SQ. Ifthe movable range of OIS is set to only the inside of the quadrangle SQ,the operating range-setting unit 184 fixes the movable range of OIS tothe quadrangle SQ (Step S14) and ends the processing of this flowchart.

If the movable range of OIS is not set to only the quadrangular arealimit as well as only the circular area limit, it is determined whetheror not it is the imaging timing of the main imaging (Step S15). If it isthe imaging timing of the main imaging, that is, if an instruction ofthe imaging to be performed by the shutter button 208 is input, theoperating range-setting unit 184 sets the flag of the quadrangular arealimit to an impossible state (Step S16) and sets the movable range ofOIS to the circle CR (Step S17). As described above, shake correctionwhere the movable range of OIS is set to the circle CR is performed atthe time of the main imaging of the static image mode. Accordingly, ashake correction effect can be ensured to the maximum extent.

If it is not the imaging timing of the main imaging, it is determinedwhether or not the flag of the quadrangular area limit is set to apossible state (Step S18). If the flag of the quadrangular area limit isset to a possible state, the movable range of OIS is set to thequadrangle SQ (Step S19) and the processing of this flowchart ends.

In contrast, if the flag of the quadrangular area limit is set to animpossible state, it is determined whether or not the position of OIS(the position of the optical axis of the vibration-proof lens 12relative to the CCD 13) is in the range of the quadrangle SQ (Step S20).If the position of OIS is in the range of the quadrangle SQ, the flag ofthe quadrangular area limit is reset to a possible state (Step S21).Then, the movable range of OIS is set to the quadrangle SQ (Step S22)and the processing of this flowchart ends.

FIG. 13 is a diagram illustrating the correctable range of thequadrangle SQ. As shown in FIG. 13, the OIS can be moved toX_(GYRO_INTEG_RECT_MIN) from X_(GYRO_INTEG_RECT_MAX) in the X directionregardless of the coordinate of OIS in the Y direction in a case wherethe movable range of OIS is in the quadrangle SQ. Likewise, the OIS canbe moved to Y_(GYRO_INTEG_RECT_MIN) from Y_(GYRO_INTEG_RECT_MAX) in theY direction regardless of the coordinate of OIS in the X direction.

As described above, shake correction where the movable range of OIS isset to the quadrangle SQ is performed in a case where it is not theimaging timing of the main imaging, that is, a live view image is to betaken in the static image mode. Accordingly, since the movable range inthe horizontal direction and the movable range in the vertical directiondo not affect each other, and subject-following performance can beensured even in a case where the panning operation and/or the tiltoperation is performed, it is easy to capture a subject on the LCDmonitor 210.

In a case where the position of OIS is outside the range of thequadrangle SQ immediately after the end of the main imaging or the like,the movable range of OIS is set to the circle CR (Step S23) and theprocessing of this flowchart ends.

Even in a case where the position of OIS is outside the range of thequadrangle SQ and the movable range of OIS is set to the circle CR, theposition of OIS gradually returns to the inside of the range of thequadrangle SQ due to the above-mentioned centering control. Further,there is also a case where the position of OIS returns to the inside ofthe range of the quadrangle SQ without depending on centering controldue to the influence of the subsequent correction of a camera shake, thesubsequent change of an angle, or the like.

In such a case, it is determined in the determination of Step S10 thatthe position of OIS is in the range of the quadrangle SQ in a case wherethe processing of this flowchart is performed again. As a result, theflag of the quadrangular area limit is reset to a possible state in StepS11, and the movable range of OIS is set to the quadrangle SQ in StepS12. As described above, in a case where the position of OIS is outsidethe range of the quadrangle SQ, the movable range is switched to thequadrangle SQ after the position of OIS returns to the inside of therange of the quadrangle SQ. Accordingly, it is possible to prevent asense of discomfort in a case where the movable range is to be switched.

According to this embodiment, the lens can be reduced in size in a casewhere the maximum movable range of OIS is set to the circle CR. Further,if the movable range is set to the quadrangle SQ included in the circleCR in a case where a live view image is to be taken, the movable rangein the horizontal direction and the movable range in the verticaldirection do not affect each other and subject-following performance canbe ensured.

In addition, since the quadrangle SQ is formed in a square shape that iscircumscribed about the circle CR, the movable range can be made aslarge as possible.

Further, in a case where the movable range is set to the circle CR, ashake correction effect can be ensured to the maximum extent during themain imaging. Furthermore, after the main imaging is completed, theposition of OIS is moved to the inside of the quadrangle SQ and themovable range is then switched. Accordingly, it is possible to prevent asense of discomfort in a case where the movable range is to be switched.

Second Embodiment

FIG. 14 is a flowchart showing a method of setting the movable range ofOIS according to a second embodiment.

First, it is determined whether or not an imaging mode is changed to thevideo mode by the operation of the operation button 212 or whether ornot a video starts to be taken by an instruction of the imaging to beperformed by the shutter button 208 (Step S31). If an imaging mode ischanged to the video mode or if a video starts to be taken, it isdetermined whether or not the position of OIS is in the range of thequadrangle SQ (Step S32).

If the position of OIS is in the range of the quadrangle SQ, theoperating range-setting unit 184 sets the flag of the quadrangular arealimit to a possible state, sets the movable range of OIS to thequadrangle SQ (Step S33), and ends the processing of this flowchart.

As described above, shake correction where the movable range of OIS isset to the quadrangle SQ is performed in a case where an imaging mode ischanged to the video mode or in a case where a video is to be taken.Accordingly, since the movable range in the horizontal direction and themovable range in the vertical direction do not affect each other andsubject-following performance can be ensured, a video of which framesare connected to each other well can be taken.

If the position of OIS is outside the range of the quadrangle SQ, theoperating range-setting unit 184 sets the movable range of OIS to thecircle CR (Step S34) and ends the processing of this flowchart. Even ina case where the position of OIS is outside the range of the quadrangleSQ and the movable range of OIS is set to the circle CR, the position ofOIS returns to the inside of the range of the quadrangle SQ due to theabove-mentioned centering control. Accordingly, the movable range of OIScan be switched to the quadrangle SQ in a case where the processing ofthe flowchart is performed again. Therefore, it is possible to prevent asense of discomfort in a case where the movable range is to be switched.

On the other hand, it is determined whether or not the exposure of themain imaging in the static image mode is being performed (Step S35) in acase where an imaging mode is not changed into the video mode or in acase where a video does not start to be taken. Here, a case where theexposure of the main imaging is being performed may be a case where theshutter button 208 is fully pressed or may include both a case where theshutter button 208 is half pressed and a case where the shutter button208 is fully pressed.

If the exposure of the main imaging is being performed, the operatingrange-setting unit 184 sets the movable range of OIS to the circle CR(Step S36) and ends the processing of this flowchart. As describedabove, shake correction where the movable range of OIS is set to thecircle CR is performed during the exposure of the main imaging.Accordingly, a shake correction effect can be ensured to the maximumextent.

If the exposure of the main imaging is not being performed, it isdetermined whether or not the position of OIS is in the range of thequadrangle SQ (Step S37).

If the position of OIS is in the range of the quadrangle SQ, theoperating range-setting unit 184 sets the flag of the quadrangular arealimit to a possible state, sets the movable range of OIS to thequadrangle SQ (Step S38), and ends the processing of this flowchart.

As described above, shake correction where the movable range of OIS isset to the quadrangle SQ is performed in a case where an imaging mode isnot changed into the video mode, a video does not start to be taken, andthe exposure of the main imaging in the static image mode is not beingperformed, that is, in a case where a live view image is to be taken.Accordingly, since the movable range in the horizontal direction and themovable range in the vertical direction do not affect each other andsubject-following performance can be ensured, it is easy to capture asubject on the LCD monitor 210.

If the position of OIS is outside the range of the quadrangle SQ, theoperating range-setting unit 184 sets the movable range of OIS to thecircle CR (Step S39) and ends the processing of this flowchart. Sincethe movable range of OIS is switched to the quadrangle SQ after theposition of OIS returns to the inside of the range of the quadrangle SQas described above, it is possible to prevent a sense of discomfort in acase where the movable range is to be switched.

According to this embodiment, since shake correction where the movablerange of OIS is set to the quadrangle SQ is performed in a case where animaging mode is changed to the video mode or in a case where a video isto be taken, a video of which frames are connected to each other wellcan be taken.

Third Embodiment

FIG. 15 is a flowchart showing a method of setting the movable range ofOIS according to a third embodiment. Portions common to the flowchartshown in FIG. 14 will be denoted by the same reference numerals as thoseof the flowchart shown in FIG. 14, and the detailed description thereofwill be omitted.

First, it is determined whether or not an imaging mode is changed to thecontinuous imaging mode by the operation of the operation button 212 orwhether or not continuous imaging is being performed by an instructionof the imaging to be performed by the shutter button 208 (Step S41).Here, a period where continuous imaging is being performed means aperiod where not only exposure on the CCD 13 is being performed but alsothe last static image from the first static image among a plurality ofstatic images are taken.

If an imaging mode is changed to the continuous imaging mode or ifcontinuous imaging is being performed, it is determined whether or notthe position of OIS is in the range of the quadrangle SQ (Step S32).Then, if the position of OIS is in the range of the quadrangle SQ, themovable range of OIS is set to the quadrangle SQ (Step S33). If theposition of OIS is outside the range of the quadrangle SQ, the movablerange of OIS is set to the circle CR (Step S34).

If an imaging mode is not changed to the continuous imaging mode and thecontinuous imaging is also not being performed, processing proceeds toStep S35. The subsequent operation is the same as that of the secondembodiment.

According to this embodiment, shake correction where the movable rangeof OIS is set to the quadrangle SQ is performed in a case where animaging mode is changed to the continuous imaging mode or in a casewhere continuous imaging is being performed. Accordingly, a plurality ofstatic images of which frames are connected to each other well can becontinuously taken.

Other Embodiments

FIG. 16 is a diagram showing the X direction that is the horizontaldirection of the imaging field of view of the imaging unit 10 accordingto the first to third embodiments, the Y direction that is the verticaldirection of the imaging field of view thereof, and the quadrangle SQthat is the limited movable range of OIS having sides parallel to the Xdirection and the Y direction, respectively. Further, the coordinate(horizontal) of the correction mechanism in the moving direction of theX slider 18 and the coordinate (vertical) of the correction mechanism inthe moving direction of the Y slider 19 are shown as the coordinates ofthe correction mechanism. The angular velocity sensor 50 detects each ofthe angular velocities in the directions of the coordinate (horizontal)of the correction mechanism and the coordinate (vertical) of thecorrection mechanism.

As described above, in the first to third embodiments, the horizontaldirection and the vertical direction of the imaging field of view areparallel to the horizontal direction and the vertical direction of thecorrection mechanism, respectively. However, the directions of thecorrection mechanism are not limited to directions parallel to thedirections of the imaging field of view.

FIG. 17 is a diagram showing an X direction that is the horizontaldirection of the imaging field of view of an imaging unit 10 accordingto another embodiment, a Y direction that is the vertical direction ofthe imaging field of view thereof, and a quadrangle SQ that is thelimited movable range of OIS having sides parallel to the X directionand the Y direction, respectively; and shows the coordinate (horizontal)of a correction mechanism in the moving direction of an X slider 18 andthe coordinate (vertical) of the correction mechanism in the movingdirection of a Y slider 19 as the coordinates of the correctionmechanism. Here, the horizontal direction and the vertical direction ofthe correction mechanism are inclined with respect to the horizontaldirection and the vertical direction of the imaging field of view by anangle of 45°, respectively.

As described above, the directions of the correction mechanism may beinclined with respect to the directions of the imaging field of view.Even in this case, the quadrangle SQ, which is the limited movablerange, is a quadrangle that has sides parallel to the horizontaldirection and the vertical direction of the imaging field of view of theimaging unit 10, respectively. Accordingly, the movable range in thehorizontal direction and the movable range in the vertical direction donot affect each other and subject-following performance can be ensured.

The quadrangle SQ is not limited to a square inscribed in the circle CR,and may be a rectangle that is included in the circle CR and has sidesparallel to the horizontal direction and the vertical direction of theimaging field of view, respectively.

Further, in the first to third embodiments, camera shake correction forthe imaging unit 10 has been performed by so-called lens shift forcontrolling the movement of the vibration-proof lens 12. However, in thecamera shake correction, the vibration-proof lens 12 and the CCD 13 maybe allowed to move relative to each other by the control of the movementof at least one of the vibration-proof lens 12 or the CCD 13. Forexample, the invention can also be applied to a case where the camerashake correction for the imaging unit 10 is performed by so-calledsensor shift for controlling the movement of the CCD 13. Further, thelens shift and the sensor shift may be combined with each other so thatthe relative movement ranges of the vibration-proof lens 12 and the CCD13 are formed as the circle CR and the quadrangle SQ.

The invention has been described in this embodiment using the digitalcamera 200 comprising the imaging unit 10, but can also be applied to amobile phone, a smartphone, a tablet terminal, and the like comprisingan imaging unit 10.

An image forming method and the method of setting the movable range ofOIS according to this embodiment may be formed as programs that allow acomputer to perform the respective steps, and may also be formed as anon-temporary recording medium, such as a compact disk-read only memory(CD-ROM), in which the formed programs are recorded.

The technical scope of the invention is not limited to the scopesdescribed in the above-mentioned embodiments. The components and thelike of the respective embodiments can be appropriately combined witheach other between the respective embodiments without departing from thescope of the invention.

EXPLANATION OF REFERENCES

-   -   10: imaging unit    -   12: vibration-proof lens    -   13: CCD    -   14: optical axis    -   15: lens barrel    -   15 a: step    -   15 b: hole    -   15 c: hole    -   16: main guide shaft    -   17: main guide shaft    -   18: X slider    -   18 a: shaft hole    -   18 b: shaft hole    -   19: Y slider    -   19 a: shaft hole    -   19 b: shaft hole    -   20: sub-guide shaft    -   21: sub-guide shaft    -   22: coil    -   23: coil    -   25: yoke    -   25 a: bent piece    -   26: permanent magnet    -   30: lens holder    -   30 a: hole    -   30 b: hole    -   32: cover    -   33: permanent magnet    -   34: permanent magnet    -   40: X Hall element    -   41: Y Hall element    -   42: magnet    -   43: magnet    -   50: angular velocity sensor    -   100: camera shake-correction device    -   111: CPU    -   115: motor driver for focusing    -   116: camera shake-correction mechanism    -   117: camera shake-correction control unit    -   119: timing generator    -   120: CCD driver    -   122: analog signal processing unit    -   123: A/D converter    -   124: image input controller    -   125: image signal processing circuit    -   126: compression processing circuit    -   127: video encoder    -   129: bus    -   130: medium controller    -   131: recording medium    -   132: memory    -   133: AF detection circuit    -   134: AE detection circuit    -   152: HPF    -   154: analog amplifier    -   156: A/D converter    -   158: HPF    -   158A: LPF    -   158B: subtractor    -   160: integration circuit    -   162: integral limiter    -   164: phase compensation circuit    -   166: control target value-arithmetic circuit    -   168: control target value limiter    -   170: subtractor    -   172: analog amplifier    -   174: A/D converter    -   176: phase compensation circuit    -   178: motor driver    -   180: VCM    -   182: controller    -   184: operating range-setting unit    -   200: digital camera    -   202: camera body    -   204: imaging lens    -   204A: lens    -   204B: lens    -   208: shutter button    -   210: LCD monitor    -   212: operation button    -   A1: angular velocity signal    -   CR: circle    -   S1: switch    -   S2: switch    -   SQ: quadrangle    -   S11 to S39: step of processing for setting movable range of OIS    -   S101 to S105: steps of camera shake-correction processing

What is claimed is:
 1. An imaging device comprising: an imaging unitthat includes an imaging element converting a received subject imageinto an image signal and an imaging lens allowing an incidence ray,which is incident from a subject, to be incident on the imaging element,at least one of the imaging lens or the imaging element being movable ina direction orthogonal to a direction of an optical axis of theincidence ray, and a maximum of a movable range of relative movement ofthe imaging lens and the imaging element being a circle; a shakedetector that continuously detects a shake of the imaging unit; and aprocessor configured to correct a shake of the subject image by movingat least one of the imaging lens or the imaging element relative to oneanother according to the detected shake; wherein the processor isfurther configured to limit the movable range of the relative movement,in which the shake of the subject image is corrected, to the inside of arectangle included in the circle in a case where imaging is performed ata frame rate by the imaging unit.
 2. The imaging device according toclaim 1, wherein the processor is configured to set the movable range ofthe relative movement to the inside of the circle in a case where astatic image is to be taken.
 3. The imaging device according to claim 1,further comprising: a display unit that displays a live view imageallowing a user to check the subject image, wherein the processor isconfigured to limit the movable range of the relative movement to theinside of the rectangle in a case where the live view image is to betaken.
 4. The imaging device according to claim 2, further comprising: adisplay unit that displays a live view image allowing a user to checkthe subject image, wherein the processor is configured to limit themovable range of the relative movement to the inside of the rectangle ina case where the live view image is to be taken.
 5. The imaging deviceaccording to claim 1, wherein the processor is configured to limit themovable range of the relative movement to the inside of the rectangle ina case where a video is to be taken.
 6. The imaging device according toclaim 2, wherein the processor is configured to limit the movable rangeof the relative movement to the inside of the rectangle in a case wherea video is to be taken.
 7. The imaging device according to claim 3,wherein the processor is configured to limit the movable range of therelative movement to the inside of the rectangle in a case where a videois to be taken.
 8. The imaging device according to claim 4, wherein theprocessor is configured to limit the movable range of the relativemovement to the inside of the rectangle in a case where a video is to betaken.
 9. The imaging device according to claim 1, wherein the processoris configured to limit the movable range of the relative movement to theinside of the rectangle in a case where continuous imaging forcontinuously taking static images is to be performed.
 10. The imagingdevice according to claim 2, wherein the processor is configured tolimit the movable range of the relative movement to the inside of therectangle in a case where continuous imaging for continuously takingstatic images is to be performed.
 11. The imaging device according toclaim 3, wherein the processor is configured to limit the movable rangeof the relative movement to the inside of the rectangle in a case wherecontinuous imaging for continuously taking static images is to beperformed.
 12. The imaging device according to claim 4, wherein theprocessor is configured to limit the movable range of the relativemovement to the inside of the rectangle in a case where continuousimaging for continuously taking static images is to be performed. 13.The imaging device according to claim 5, wherein the processor isconfigured to limit the movable range of the relative movement to theinside of the rectangle in a case where continuous imaging forcontinuously taking static images is to be performed.
 14. The imagingdevice according to claim 1, wherein the rectangle is inscribed in thecircle.
 15. The imaging device according to claim 1, wherein therectangle is a square.
 16. The imaging device according to claim 1,wherein the rectangle has sides parallel to a horizontal direction and avertical direction of an imaging field of view of the imaging unit,respectively.
 17. The imaging device according to claim 1, wherein theprocessor is configured to limit the movable range of the relativemovement to the inside of the rectangle after relative positions of theimaging lens and the imaging element enter the rectangle.
 18. Theimaging device according to claim 1, wherein the processor is configuredto move the imaging lens.
 19. The imaging device according to claim 1,wherein the processor is configured to move the imaging element.
 20. Animaging control method comprising: an imaging step of imaging a subjectby an imaging unit that includes an imaging element converting areceived subject image into an image signal and an imaging lens allowingan incidence ray, which is incident from the subject, to be incident onthe imaging element, at least one of the imaging lens or the imagingelement being movable in a direction orthogonal to a direction of anoptical axis of the incidence ray, and a maximum of a movable range ofrelative movement of the imaging lens and the imaging element being acircle; a shake detection step of continuously detecting a shake of theimaging unit; and a correction step of correcting a shake of the subjectimage by moving at least one of the imaging lens or the imaging elementrelative to one another according to the detected shake, wherein themovable range of the relative movement, in which the shake of thesubject image is corrected, is limited to the inside of a rectangleincluded in the circle in a case where imaging is performed at a framerate in the imaging step.